The long-term climatology of Mid-Mississippi Valley dewpoints and the implications for regional climate

Using data obtained from the Midwest Climate Center, the long term climatological character of surface dewpoints in Missouri and Arkansas were examined. The dewpoint data from from this region demonstrates that there has been a long-term upward trend in the dewpoint data since 1948, and these trends were statistically significant at the 90 and 95% confidence level. These trends were level or more slowly upward from 1948 until the late 1970s,or during a time when temperatures were cooling. Dewpoint trends displayed stronger trends from the late 1970s until the present time. Examining ENSO variability revealed that dewpoints were higher during El Nino winters, and lower (drier) during La Nina springs and summers. These drier dewpoint correspond with less precipitation and enhanced fire threat. An examination of the 500 hpa heights reveal that the summer season ridgingduring La Nina years was consistent with drier conditions as well.